A conventional domestic oven includes an enclosure comprised of sheet metal coated with enamel. At least one heating device is provided inside the enclosure to generate heat for baking food, such as bread. The heating device is typically mounted at the bottom of the enclosure and may be a gas burner, or an electric resistance heating element.
The heating element heats the air at the bottom of the enclosure, thereby creating a temperature gradient that causes the heated air to rise and circulate within the enclosure. The circulating air heats the walls and roof of the enclosure, charging the oven until the thermostat indicates that it has reached a desired temperature. At this point, food being baked, including, for example, bread is disposed in the enclosure, and is then baked by the combination of ambient heat from the heated air, and radiant heat from the heating element and the heated walls of the enclosure.
Typically, the heating device is cycled on and off in response to air temperature in the enclosure, which will vary because of the temperature gradient and insulatory capacity of the oven, and when the oven door is opened. It is also dependent upon the thermal retention properties of the enamelized metal, which is generally conductive and does not store heat as efficiently as other baking materials. As a result, the temperature around the food material may fluctuate by as much as 75.degree. F. during the baking process. Such temperature fluctuations cause cooking to occur unevenly. In the case of baking bread, such thermal fluctuations result in lack of uniformity in rising, surface color, and crust development, and in certain instances cause burning of the bread.
In commercial hearth ovens, heat fluctuations are moderated by the use of refractory insulatory materials that retain and dispense heat in a far more efficient and uniform manner than their domestic enamelized metal counterparts. Additionally, for baking bread, the direct contact between the specialized material in the commercial oven and the dough itself, causes a different style of baking--one that simply cannot be effectively achieved in a standard domestic oven. Moreover, commercial hearth ovens are expensive and large, and hence do not find their typical place in a domestic home.
Baking stones are sometimes inserted in domestic ovens as a "heat sink" to retain heat for more even baking. However, such conventional baking stones are typically rectangular, with planar surfaces and a narrow thickness. Such baking stones, however, do not retain a large amount of heat and emit heat only in one direction with regard to the bread. Most importantly, because the stone lacks side walls, food material like bread is heated even less uniformly than in a typical domestic oven, especially because the side heat dispensed to the food material arises predominantly from the enamelized side walls. As a result, the chamber of insulatory material that is provided in a commercial hearth oven is in no manner recreated in a domestic oven when a baking stone is merely used.
In an attempt to overcome the restrictions inherent in a domestic oven, Krohe, in U.S. Pat. No. 4,127,108 shows a device comprised of a refractory stoneware which is essentially a completely enclosed chamber that is placed in the domestic oven, and, after heating, the domestic oven is then shut off. Krohe, however, fails to utilize certain of the advantages of a domestic oven, and to combine those advantages with certain of the advantages of stoneware. As a result Krohe is almost a "mini" commercial hearth oven placed in a domestic oven. Beyond the mere limitation in space thereby created and the resultant inability to bake anything other than rye bread, Krohe fails to utilize the thermal radiant heat properties of the roof of a domestic oven, and thus has not effectively solved the problem.
U.S. Pat. No. 4,706,832 to Citino essentially shows a cookie sheet (comprised of aluminum) having a plurality of quarry tiles placed upon the sheet, for insertion into a domestic oven. This device fails to achieve the desired results because the materials selected are of insufficient density and thickness to retain necessary heat to improve baking, the discontinuity in the tiles is apt to create thermal pockets, and the absence of side wall enclosure allows the enamelized walls of the conventional domestic oven to burn bread and other food material that is baked.
Accordingly, there is a need in the art for a baking device that can be inserted into a domestic oven to provide the substantial equivalent of a commercial hearth oven with a minimum of materials, utilizing materials having the necessary thermal properties, proper dimensions, and proper configuration to combine certain of the beneficial properties of the domestic oven with the thermal capacitive properties of stoneware.